Some tree delimbers include a pair of curved knives that can be brought into contact with the outer surface of a log. The log is pulled past the knives which shear off any limbs projecting from the log. In typical tree delimbers the log is moved by compressing it between a pair of counter-rotating feed rollers. The feed rollers grip the log and move it along. Examples of tree delimbers which work in this general manner are the SIDEWINDER™ and LIM-MIT™ delimbers made by Risley Manufacturing Ltd. of Grande Prairie, Alberta, Canada.
Some existing feed rollers are faced with spikes to enable them to better grip the outer surface of a log. These spikes can incise the outer layer of wood of the log, which is undesirable.
Other commonly-used feed rollers comprise a rubber-coated cylinder having a chain mesh stretched over its outer surface. These feed rollers, while reducing damage to the log surface, suffer from relatively short service lives and can be undesirably expensive.
Commonly-owned U.S. Pat. No. 4,972,890 describes a type of feed roller which comprises a cylindrical drum having contour-edged bars bolted to its outer surface. The contour-edged bars are relatively widely spaced apart. These feed rollers have not been completely successful, because they can cause chipping of the outer surface of logs.
Despite the variety of feed rollers available for use in tree processing machinery there remains a need for feed rollers which improve on the performance and/or cost effectiveness of current feed rollers.